Permanent deletion of voice mail messages

[ Edited ]

Is there a way to have voice mail messages permanently be deleted when the are removed from my iPhone using the delete button in the visual voice mail screen? What happens now is if I delete a voice message from this screen it still will be in my voice mail box with the only way to delete it is going into voice mail the old fashioned way (holding the "1" key down) and deleting them one by one. I found this out the hard way when I received a call from someone telling me that my voice mail was full when I thought I had none. Also speaking of voice mail, is there a way to save multiple greetings so they are easy to change?